1. Field of the Invention
This invention relates to nonvolatile resistive memory elements, and more particularly, to a nonvolatile resistive memory element with an oxygen-gettering layer.
2. Description of the Related Art
Nonvolatile memory elements are used in devices requiring persistent data storage, such as digital cameras and digital music players, as well as in computer systems. Electrically-erasable programmable read only memory (EPROM) and NAND flash are nonvolatile memory technologies currently in use. However, as device dimensions shrink, scaling issues pose challenges for traditional nonvolatile memory technology. This has led to the investigation of alternative nonvolatile memory technologies, including resistive switching nonvolatile memory.
Resistive-switching-based nonvolatile memory is formed using memory elements that are bistable, i.e., having two stable states with different resistances. A bistable memory element can be placed in a high resistance state or a low resistance state by application of suitable voltages or currents. Voltage pulses are typically used to switch the bistable memory element from one resistance state to the other. Subsequently, nondestructive read operations can be performed on the memory element to ascertain the value of a data bit that is stored therein.
As resistive switching memory device sizes are scaled downward in size, it is important to reduce the required forming voltage for devices as well as switching current and voltage, i.e., the current and voltage that are necessary to reliably set, reset and/or determine the desired “on” and “off”states of the device. Reduction of the switching voltage and current minimizes power consumption of the device, resistive heating of the device, and cross-talk between adjacent devices.
In resistive switching devices that use a silicon dioxide (SiO2) layer together with a high-K dielectric layer to perform resistive switching, the thickness of the silicon dioxide layer strongly affects the required forming voltage, switching current, and switching voltage of the device. If the silicon dioxide layer in a resistive switching device is too thick, the forming voltage, switching current, and switching voltage of the device are undesirably high. If the silicon dioxide layer in the resistive switching device is too thin, bistable switching may not occur reliably.
In light of the above, there is a need in the art for nonvolatile resistive switching memory devices that have a silicon dioxide layer that is neither too thick nor too thin.